High duty fuse switch



Feb. 22, 1938. R. R. PITTMAN ET AL 2,109,090

HIGH DUTY FUSE SWITCH I Filed Jan. 1e, 1957 a sheets-sheet 1 vENToR ATTORN EY Fzy. 2

Feb. 22, 1938. R. R, plTTMAN ET AL 2,109,090

HIGH DUTY FUSE SWITCH Filed Jan. 16, 1937 2 Sheets-Sheet 2 INVENTOR ATTOR N EY Patented Feb. 22, 1938 lUNITED STATES PATENT OFFICE Blu if, Ark.

Application January 16, 1937, Serial No. 120,962

17 Claims.

'Ihis invention relates generally to fuse switches Y used for the purpose of protecting high tension electrical circuits against excessive over currents, and particularly to the type of fuse switch known in this art as dropout switches, i. e., a combined switch and fuse in which thefuse cartridge of the device is actuated to the open switch position in response to the rupture of a fusible element. Switches of this type are not new in this art; one of the first being disclosed in a patent dated Nov. 15, 1910, No. 975,431, issued to R. P.

Jackson. i

The present invention has for its principal object an improved structure for the purpose of providing a fuse switch of this general type having relatively high power interrupting ability in comparison to prior art structures, through the provision of means for controlling and expanding the gases generated under high pressures incident to such duty.

More specically, among the objects of the present-invention may be noted (1) means responsive to the blowing of a fuse link within the cartridge of the device for closing a vent at the upper end of the cartridge and removing a closure from the lower end, and at the same time releasing the cartridge from the closed switch position; (2) the arrangement for relieving the high pressures within the cartridge due to the interruption of relatively large currents at two points and in such a manner that the recoil will maintain the switch in the closed position until the gaspressure has been greatly reduced; (3) the provision of means for progressively closing a vent atA the upper end of the cartridge and at the same time progressively increasing the volume of the hollow within the cartridge to avoid impact; (4) the provision of resilient means for absorbing the initial impact due to the interruption of heavy current by permitting an upward travel of the cartridge, together with means .for limiting the extent of such travel; (5) an arrangement of vents such that, under normal conditions, the entrance of rain or insects are excluded from the cartridge, but which exhaust the gases under conditions of operation in such a manner and direction as to prevent short circuits due to gaseous conducting iiame and (6) a new, simple and effective fuse switch having relatively great interrupting ability.

Withthese and other objects in view as may later appear, our invention resides in the novel form of the elements making up the device, and their arrangement and combination.

In the drawings (2 sheets):

Fig. 1 is a side elevational view of the device, shown partly in section.

along the line II-II in Fig. 1.

Fig. 3 is a plan view of the upper end of the fuse cartridge of the device.

Fig. 4 is an enlarged fragmentary sectional elevation of the upper end of the fuse cartridge.

Fig. 5 is a fragmentary front view of the exhaust vent or opening at the upper end of the cartridge.

Fig. 6 is a plan view, as seen from below, of the upper terminal member.

By reference to Fig. 1, we will first describe the fuse cartridge mounting, which includes the metal base I0, the spaced insulators II and I2 suitably mounted thereon, and the upper and lower conducting terminal members I6 and 46, which are respectively secured to the upper and lower insulators by means of the bolts I3 and 45. For convenience in connecting the device in a circuit, the line terminal I4 is arranged in positive electrical contact with the upper terminal member I6, and is provided with a nut I5 for engaging a line wire; similarly, the load terminal 43 is arranged in positive electrical contact with the lower terminal member 46, and is provided with the nut 44 for engaging a load wire.

The upper terminal member I6, as shown-in Figs. 1 and 6, comprises the channel-shaped forwardly extending portion which serves as a weather shed for the upper parts of the device. The upper terminal member contact I'I is supported between the vertical channel walls on the pivot 20, and extends forwardly therefrom along and within the channel section. Intermediate of its ends, the upper terminal member contact is provided with a cylindrical recess I 9, between the bottom of which and the upper inner surface of the channel member is interposed the spring I8;

the latter continually biasing the upper terminal contact member II. in a clockwise direction about the pivot 20. Forwardly from the recess I9, the upper terminal contact member I1 is provided with an inwardly and upwardly arcuate surface, beyond which it is upwardly sloped to its end. To prevent damage to-the spring I8 and/or the pivot 20 due to thermal eiects of electrical current therethrough, the upper terminal contact member I1 is electrically connected to the channel member by the flexible conductor 2I, which is attached to these members by means of the screws 22, 23 and 24.

The lower terminal member 46, as illustrated in Figs. 1 and 2, is arranged with its lower portion extending forwardly, downwardly and then upwardly from the outer end of the lower insulator I2, in the form of a hook-shaped yoke, to provide a pair of bearing hooks 49. The upper portion of the lower terminal member terminates at its outer or forward end in the form of a yoke, the arms of which are designated by the numeral 54.

Having described the mounting for the fuse cartridge, we now describe the expulsion fuse cartridge itself, with particular reference to Figs. 1, 3, 4, and 5.

The fuse tube or tubular insulator 25, of any suitable insulating material adapted for expul- 'sion fuses, such as ber, is provided near its lower end with the lowerl metal cartridge sleeve 50. which is rigidly attached to the lower end of l the tubular insulator 25 by means of the screws 52. The metal sleeve 50, near its lower end, is provided with the oppositely and laterally extending integral pins of suitable size for resting in and rotating about the hooks 49 of the lower terminal member 46. A slotted portion 53 of the lower sleeve 50 extends outwardly therefrom, and is threaded for cooperation with the screw plug 41, for the purpose of clamping securely the lower end of the fuse link 42.

At its upper end, the fuse tube 25 has rigidly secured thereto, by means of the pin 24, the upper fuse cartridge sleeve 3|. An eye 33, for con'- venience in manually manipulating the switch, is formed integrally with the sleeve 3|, and extends outwardly therefrom from the lower portion thereof. Immediately above the eye 33, a vent opening or recess 32 is formed, and arranged to register with the opening 55 through the wall of the tubular insulator 25. To prevent entrance of insects, the outer face of the vent 32 is preferably perforated, as indicatedby the numeral 4I) in Fig. 5. y

An integral portion of the sleeve 50 extends inwardly, in a direction opposite from that of the vent, and has attached thereto, by means of the pivot 28, the upper contact 26 of the fuse cartridge. The contact 26 extends upwardly and inwardly from the pivot 28, being rounded at its upper end to provide, under conditions to be later explained, a contact with the upper terminal member contact I1. Intermediate of the ends of its upwardly and inwardly extending portion, the upper contact 26 of the fuse cartridge is provided with an integral portion arranged to extend outwardly toward the upper end of the fuse cartridge, this portion terminating in the form of an open yoke, as shown in detail in Fig. 3.

The tubular metal upper fuse terminal 35 of the fuse cartridge is arranged for reciprocatory movement within the enlarged upper portion 39 of the fuse tube 25, and its`reciprocatory motion is limited by the engagement of the upper and lower end walls of the longitudinal recess 31 with the retaining pin 34. 'Ihe upper end of the fuse terminal 35 is arranged` with internal threads for cooperation with the threads of the screw plug 38, for attaching the upper'end of the fuse link to the fuse terminal 35. A exible conductor 21, attached at one end to the fuse terminal 35 by means of the screw 29, and at the other end to the upper contact 26 of the fuse cartridge by means of the screw 30, provides a. path for shunting current around the pivot 28. An opening 36 through the wall of the fuse terminal 35 is arranged to register with the openings 55 and 32 only when the fuse terminal 35 is in its lowermost position, and to close the opening 55 upon upward movement of the fuse terminal 35 axially with respect to the cartridge 25. The member 35 thus is a slide valve for opening and closing 'the opening 55, the latter extending laterally extending integral portions 4| of the fuse terminal 35.

In operating the device, the fuse link 42 is rst dropped from the top through the fuse terminal 35 and the tubular insulator 25, and secured to the former by the plug 38. 'I'he fuse link is then passed through the closure 48, and the latter pressed against the bottom of the fuse tube 25, and then crimped or squeezed on the lower portion of the fuse link to retain the closure 48 in place. The closure 48 is conveniently made of lead or any similar easily deformed metal. The lower end of the fuse link 42 is then secured to the lower fuse link terminal 53, as before des scribed.

The fuse cartridge is then rotated on the pivots 5| from the position indicated by the broken lines in Fig. 1 to the closed position shown by the solid lines of the same figure. It will now be observed that the upper end of the cartridge is vented; the lower end is closed; and that the fuse link is under tension due to the downward force of the spring I8, which is transmitted about the pivot 28 through the upper contact 26 of the fuse cartridge to the outwardly extending` portions 4| of the fuse terminal 35. The cartridge is thus latched in the closed circuit position through the l engagement of the detent means 4| with the upvfuses the fuse link 42, the internal pressure within the cartridge will rst be relieved through the vent 32. The reaction from such exhaust is obviously in a direction to rotate the fuse cartridge in a. counterclockwise direction; that is, in a direction to maintain the cartridge in the closed position. In response to the rupture of the fuse link, the closure 48 is removed from the lower end of the cartridge as the fuse terminal 35 moves upwardly to cut off the exhaust from the vent 32. As the valve means comprising the members 35 and 32 shut oi the vent at the upper end of the cartridge, the upward movement of the fuse terminal 35 adds volume to the inside of the cartridge to reduce impact. Also, the upward movement of the fuse terminal 35 permits the counterclockwise rotation of the upper fuse cartridge contact 26 about the pivot 28 with respect to the axis of the fuse cartridge under the influence of the spring I8, thus releasing and forcing outwardly from the upper terminal member the upper end of the fuse cartridge. The cartridge then assumes, under the influence of gravity, the i full open switch position illustrated by thev broken lines of Fig. 1.

rIhe opening of the bottom of the cartridge, when it is under high internal pressure, through the removal of the closure 48, will tend to force the cartridge upwardly. The resilient spring I8 absorbs the initial shock from such reaction, the initial upward impact being transmitted from the cartridge 25 to the spring I8 through the members 3|, 28, 26 and |1. 'I'he upward motion deforms the spring |8 an amount a little less than the spacing between the member I1 and the member I6. 'I'he upward motion is limited by the contact of the upper edge of the lower fuse cartridge sleeve 50 with the underside of the overhanging portions 54 of the lower terminal member 46. The stressis thus divided between the two insulators and I2, instead of being entirely imposed on one of them.

It may be noted that the drganization is such that the port 32 is closed, and the closurel 48 is ruptured, before the fuse cartridge 25 is unlil latched. Such an arrangement assures that the arc within the cartridge 25 will be completely extinguished before the member 26 moves away from the member I1. In the event that the cartridge 25 was not arranged to be held in position by the recoil of the exhaust gases from the port 32 and the lower end of the cartridge until complete extinguishment of the circuit-interrupting arc has occurred, then serious burning of the members 26 and I1 would occur. In ourdevice, under heavy currents, the arc may possibly be extinguished before the port 32 completely closes. Under relatively smaller currents, the internal gas pressure will necessarily be less, and arc extinguishment relatively more diicult. 'I'he closing of the port 32 under this condition before unlatching the cartrid-ge 25 leaves the latter vented at only the lower end, resulting in higher internal pressures at these current values and assuring arc extinguishment over a range of currents equivalent to that of cartridges open at both ends and open at only one end, this wide range of effective arc extinguishment being attained in a single device. It may also be observed that the shock which might attend the sudden closing of the port 32 by the valve 35 is cushioned by the axial movement of the latter outwardly from the tube, since this movement increases the internal volume under pressure as the port 32 is closed.

Among other things, it may be noted that our device cannot be placed in the service position unless the opening 55 through the wall of the fuse cartridge is open; also that the cartridge cannot be unlatched from the upper terminal member in response to the blowing of the fuse unless the vent is closed, or after such time as the internal pressure has been greatly reduced.

While we have herein specifically described one embodiment of our invention for the purpose of facilitating an understanding of its construction and operation, it will be understood that changes in this specific construction may be made without departing from the principles of the invention.

We claim, as our invention:

1. A fuse switch comprising insulating means having mounted thereon spaced insulated upper and lower terminal members, a fuse cartridge pivoted at its lower end n the lower terminal member, a fuse link within said cartridge electrically connecting the terminal members, latch means dependent upon tension in said fuse link for maintaining the electrical connection, an opening at the upper end of said cartridge and a valve longitudinally movable along the axis thereof for closing said opening, and detent means carried by said valve, said detent means beingarranged to prevent movement of said latch means in response to the rupture of said fuse link when said opening is open.

2. In a fuse switch, spaced insulated upper and lower terminal'members, a fuse cartridge pivoted on the lower terminal -member and latched to the upper terminal member, a fuse link within said cartridge electrically connecting said terminal members, means controlled by tension in said fuse link for maintaining said switch in the closed position when said fuse link is unfused, and for unlatching said cartridge and opening said switch following the rupture of said fuse link, said cartridge being vented at its upper end, said vent being arranged so that the recoil due to discharge of gas therethrough maintains the cartridge in the closed position.

3. In a fuse switch, spaced insulated upper and 75 lower terminal members, a fuse` cartridge pivoted on the lower terminal member and latched to the upper terminal member, a fuse link within said cartridge electrically connecting said terminal members, means controlled by tension in said fuse link for maintaining said switch in the closed position when said fuse link is unfused, and for unlatching said cartridge and opening said switch following the rupture of said fuse link, said cartridge being vented at its upper end and closed at its lower end when said fuse link is intact, and means responsive to the rupture of said fuse link for opening the lower end of said cartridge, said upper vent and the lower end of said cartridge being related to each other and to the other elements of said switch so that the combined recoil due to the discharge of gas from said cartridge maintains the latter in the closed position.

4. In a fuse switch having an open and a closed position, spaced insulated upper and lower terminal members, a fuse cartridge pivoted on the lower terminal member, a fuse link within said cartridge electrically connecting said terminal members, latch means combined with the upper terminal member and controlled by tension in said fuse link for maintaining said cartridge in the closed position, said latch means including a resilient member permitting an upward movement of said cartridge against the bias of said resilient member in response to expulsion action within said cartridge, and means combined with the lower terminal member for limiting the upward travel of said fuse cartridge.

5. In a fuse switch having an open and a closed position, spaced insulated upper and lower terminal members, a fuse cartridge pivoted on the lower terminal member, a fuse link within said cartridge electrically connecting said terminal members, latch means combined with the upper terminal member and controlled by tension in said fuse link for maintaining said cartridge in the closed position, said latch means including a resilient member permitting an upward movement of said cartridge against the bias of said resilient member in response to expulsion action within said cartridge, and means including a member rigidly secured to said lower terminal member and positioned in the path of upward movement of a portion of said fuse cartridge for limiting the upward travel thereof.

6. A fuse switch comprising insulating means having mounted thereon spaced insulated upper and lower terminal members, a fuse cartridge pivoted at its lower end on the lower terminal member, a fuse link within said cartridge electrically connecting the terminal members, latch means dependent upon tension in said fuse link for maintaining the electrical connection, an opening at the upper end of said cartridge and a valve longitudinally movable along the axis thereof for closing said opening, and detent means carried by said valve, said detent means being positioned externally of said cartridge and arranged to actuate said latch means in response to rupture of said fuse link.

'7. A fuse switch comprising insulating means having mounted thereon spaced insulated upper and lower terminal members, a fuse cartridge pivoted at its lower end on the lower terminal member,.a fuse link within said cartridge electrically connecting the terminal members, latch means dependent upon tension in said fuse link for maintaining the electrical connection, an opening at the upper end of said cartridge and a valve longitudinally movable along the axis thereof for closing said opening, said valve including detent means positioned externally of said cartridge and arranged to actuate said latch means in response to a movement of saidvalve in a direction to close said opening.

8. A fuse switch comprising insulating means having mounted thereonspaced insulated upper and lower terminal members, a fuse cartridge pivoted at its lower end on the lower terminal member, a fuse link Within said cartridge electrically connecting the terminal members, latch means dependent upon tension in said fuse link for maintaining the electrical connection, an opening at the upper end of said cartridge and a valve longitudinally movable along the axis thereof for closing said opening, said valve including detent means positioned externally of said cartridge and arranged to restrain movement of said latch means when said opening is open and to release said latch means in response to movement of said valve in a direction to close said opening.

9. An expulsion fuse comprising a hollow tube of insulating material, conducting contacts at the respective ends of said tube, one of said contacts being formed with an opening communicating with the interior of said tube, a valve movable between the open and the closed position associated with said opening, and a fuse link within said tube electrically connecting said contacts, said fuse link being fastened to said valve and arranged to hold said valve in the open position when said fuse link is unfused.

10. An expulsion fuse comprising a hollow tube of insulating material, conducting contacts at the respective ends of said tube, one of said contacts being formed with an opening communicating with the interior of said tube, a valve movable between the open and the closed position associated with said opening, and a fuse link within said tube electrically connecting said contacts, said fuse link being secured to said valve and arranged to normally hold said valve in the open position.

11. An expulsion fuse comprising a hollow tube of insulating material, conducting contacts at the respective ends of said tube, one of said contacts being formed with an opening communicating with the interior of said tube, a valve movable between the open and the closed position asso-V ciated with said opening, a. fuse link within said tube electrically connecting said contacts, and fuse terminals externally of said tube for engaging the respective ends of said fuse link, said fuse link being fastened to said valve and arranged to hold said valve in the open position when said fuse link is unfused.

12. An expulsion fuse comprising a hollow tube of insulating material, conducting contacts at the respective ends of said tube, one of said contacts being formed with an opening communicating with the interior of said tube, a valve movable between the open and the closed position associated with said opening, a fuse link within said tube electrically connecting said contacts, and fuse terminals externally of said tube for engaging the respective ends of said fuse link, said fuse link being fastened to said valve and arranged to hold said valve in the open position when said fuse link is unfused, and to release said valve in response to the blowing of said fuse, the arrangement being such that said valve moves in response to pressure within said tube to the closed position.

13. The combination in an expulsion fuse normally having an opening at one end thereof in communication with the interior of said fuse and means closing the other end of said fuse, of means responsive to the blowing of said fuse for closing the opening at said one end and removing the means closing said other end.

14. An expulsion fuse comprising a hollow tube of insulating material, conducting contacts at the respective ends of said tube, one of said contacts being formed with an opening in communication with the interior of said tube, a fuse link within said tube electrically connecting said contacts, a movable valve arranged to close said opening, one end of said fuse link being fastened to said valve whereby the movement thereof is restrained when said fuse link is unfused and released upon the fusing of said fuse link, and means for generating a gas under pressure within said tube in response to the fusing of said fuse link, the arrangement being such that said valve is actuated to close said opening in response to the gas pressure within the tube.

15. An expulsion fuse comprising a hollow tube of insulating material, conducting contacts at the respective ends of said tube, one of said contacts being formed with an opening in communication with the interior of said tube, a fuse link within said tube electrically connecting saidvcontacts, a movable valve arranged to close said opening, one end of said fuse link being fastened to said valve whereby the movement thereof is restrained when said fuse link is unfused and released upon the fusing of said fuse link, means for initiating an arc within said tube in response to the fusing of 'said fuse link, and means dependent upon the duration of said arc for actuating said valve to close said opening.

16. An expulsion fuse comprising a hollow tube of insulating material, conducting contacts at the respective ends of said tube, one of said contacts being formed with an opening in communication with the interior of said tube, a fuse link within said tube electrically connecting said contacts, a movable valve arranged to close said opening, one end of said fuse link being attached to said valve whereby the movement thereof is restrained when said fuse link is unfused and released upon the fusing of said fuse link, means responsive to an arc within said tube for generating a gas under pressure therein upon the fusing of said fuse link, and means responsive to the gas pressure for actuating said valve to close said opening and change the direction of discharge of said gas from said tube whereby said arc is extinguished.

17. A fuse switch comprising insulating means having mounted thereon spaced upper and lower terminal members, a fuse cartridge pivoted at its lower end on the lower terminal member, an opening at the upper end of said cartridge and a valve for closing said opening, a fuse link within said cartridge electrically connecting the terminal members, one end of said fuse link being fastened to said valve and arranged to hold said valve in the open position, latch means dependent upon tension in said fuse link for maintaining the electrical connection, and detent means carried by said valve externally of said cartridge and in engagement with said latch means, the arrangement being such that said valve is movable to the closed position independent of said latch means.

RALPH R. PI'ITMAN. CARROLL H. WALSH. 

